Who started this one? For years, Twitter was accurately referred to as a microblogging service. But in the past year or two, suddenly everyone lumps it in with Facebook as a "social network." Pinterest, too.

They're not social networks. Twitter and Pinterest are blogging services in the same category as Tumblr, Blogger and Posterous (acquired by Twitter in March) -- services that let you publish your words, along with links and pictures, to lists of people who follow you. The only fundamental difference between Twitter and Tumblr, for example, is arbitrary limits on the number of characters you can post on Twitter.

Yes, Twitter and Pinterest are "social." But what isn't social these days?

And since everything is "social," we need reasonable criteria for what we mean when we use the phrase "social network," to distinguish actual social networks like Facebook and Google+ from social blog sites, social video sites, social whatever sites.

Some things are and should be defined by the existence of multiple features. For example, a home is defined in part by the existence of facilities for sleeping and eating and bathing and so on. It’s not one of these features, but all of them that makes a home a home.

A bathroom by itself is not a home. A kitchen by itself is not a home. A "home" by definition is a building with multiple basic functions for living.

A "social network" also requires a combination of communications media. Facebook, the quintessential social network, let's people broadcast status updates, post on walls, poke, chat, message, Skype, comment, upload pictures and more. It’s these multiple avenues of interaction that make a social network a social network.

Twitter is just “status updates.” Pinterest is just pictures with captions. As such, they don’t qualify as “social networks.” They can’t be meaningfully categorized with Facebook and Google+.

So let's stop being sloppy with language. Twitter and Pinterest are not social networks.

2. Social networking is for the young.

Everybody talks about social networks as the exclusive province of the 18-24 crowd. In fact, all ages are heavily represented on all the social networks.

About two years ago, a rash of studies shocked everyone by pointing out that older people are more active on social networks than younger people. In fact, as of 2010, the biggest segment of users was in the 35-44 age group. The second biggest segment was users in the 45-54 group. And even the 55-64 year old group was slightly larger than the 18-24 crowd. A whopping 79% of all social media users were over the age of 24.

3. Everybody loves Facebook.

Predictions for Facebook's IPO were all over the map. Most experts thought Facebook would do great right off the bat. They haven't.

The conventional wisdom about Facebook was that seasoned, professional investors wanted nothing to do with it. The IPO was too heavily hyped to be a good investment, and the fundamentals and direction of the business too unclear.

But not to worry, we were told. Facebook's rabidly enthusiastic fans would gobble up the stock out of pure love.

It didn't happen. Why? Because people don't love Facebook.

Facebook is the Microsoft Windows of social networks. It makes practical sense to be on Facebook because everyone else is on it. But real passion about Facebook itself is hard to find.

People love the people they love, and the people they love are on Facebook. But nobody loves Facebook.

4. Nobody loves Google+.

Google+ is the Macintosh of social networks, the service with fewer but far more passionate users.

In fact, the original Mac evangelist, Guy Kawasaki, recently called Google+ the Macintosh of social networks, and said that seeing Google+ for the first time was a "religious experience," just like when he saw the Mac for the first time.

People love Google+.

5. Google+ is a "Ghost Town."

Pundits and writers keep repeating the myth that Google+ is a "ghost town," a service that nobody uses.

Meanwhile, pop star Britney Spears recently passed the 3 million followers mark on Google+, only eight months after Google+ opened to the public.

Ashton Kutcher was the first person to reach 3 million followers on Twitter, a milestone reached in the summer of 2009, a full three years after Twitter launched.

Eight months vs 36 months to reach the same milestone.

Google+ is the opposite of a ghost town; it's a riot of user activity, and growing faster than Twitter or Facebook ever did.

The "ghost town" myth comes from the measurement of public posts and public activity, and does not account for private posts and, doing things like following and reading about and commenting on and sharing and doing Hangouts.

To accept incredibly narrow and misleading data as truth is stupid.

It's like measuring how much food is eaten nationally by looking at only restaurants, and ignoring food eaten at home, school, work or in cars.

Google+ is not a “ghost town.” It’s the fastest-growing, most active new social network ever launched.